Application Ser. No. 683,603 filed Dec. 12, 1984, and now U.S. Pat. No. 4,724,240 which is herewith incorporated by reference, discloses solid compositions wherein a functional group is entrapped in the lattice of a crosslinked hydrophobic polymer during in situ polymerization of the monomers forming the polymer lattice.
U.S. Pat. No. 4,587,129 of Kliment, which is incorporated herein by reference, discloses a solid slow release hydrogel composition consisting of a flavor or a fragrance entrapped in a hydrophilic copolymer.
It is known to impregnate plastic articles having a high porosity with materials that have medicaments, volatile germicides, disinfecting agents, and the like. Such materials are generally polymeric carriers as disclosed in U.S. Pat. Nos. 3,857,932 and 4,202,880.
U.S. Pat. No. 4,339,550 of Palinczar relates to the incorporation of volatile materials into hydrophilic polyurethane foam for purposes of a sustained release of the materials.
U.S. Pat. No. 4,309,509 of Wood discloses an odorant containing foam prepared by reacting a prepolymer with an aqueous reactant containing a volatile odorant which is diffused into the air.
U.S. Pat. No. 4,590,111 of Takeuchi discloses a fragrance releasing sheet article having a pattern member which is formed of a thermoplastic or thermosetting resin and a fragrance releasing member composed of a thermoplastic or thermosetting resin and perfume.
Styrene-divinylbenzene copolymer, which is one crosslinked polymer that is useful in the practice of the present invention, can be prepared as described in U.S. Pat. No. 4,291,980 of Patterson or the article of Patterson entitled, "Preparation of Cross-Linked Polystyrenes and Their Derivatives for Use as Solid Supports or Insoluble Reagents" in Biochemical Aspects of Reaction on Solid Supports, Stark, ed. Academy Press, pp. 189-213, 1971.
Attempts have been made in the past to incorporate high levels of functional components into thermoplastic and thermoset resins. However, high levels of functional materials incorporated into resins usually results in the sacrifice of beneficial physical properties. Polystyrene cannot tolerate fragrances or similar compounds because of the negative effect on mechanical properties. Polyolefins and polyvinyl chloride can only tolerate low levels before dramatic distortions on the mechanical properties are experienced. Polyurethanes have been successfully foamed in situ in combination with fragrances and biocides. However, the number of functional groups which may be incorporated is limited because of side reactions with some functional materials during the foaming process.
The art is replete with attempts to render functional materials amenable to release on demand when incorporated in a resinous material. Encapsulation confines materials in discrete units or capsules as a result of coating particles of the material with an encapsulant. The coating wall or encapsulating material used in encapsulation includes natural or synthetic polymers which permit release of the functional material by fracture, degradation, or diffusion. A uniform sustained release of the functional material is not usually possible.
The incorporation of more than one functional component into plastic materials can result in problems during manufacturing since the high temperatures that the plastics are worked could cause loss or reaction of the functional components and deactivation for their intended purposes. Melt spinning or casting of synthetic fibers is one of such instances where functional components may volatilize or react with functional end groups of the polymer.